Catalytic System‐Controlled Divergent Reaction Strategies for the Construction of Diversified Spiropyrazolone Skeletons from Pyrazolidinones and Diazopyrazolones
Feifei Fang, Shulei Hu, Chunpu Li, Qian Wang, Run Wang, Xu Han, Yu Zhou, Hong Liu
Abstract
Abstract A catalytic system‐controlled divergent reaction strategy was here reported to construct four types of intriguing spiroheterocyclic skeletons from simple and readily available starting materials via a precise chemical bond activation/[ n +1] annulation cascade. The tetraazaspiroheterocyclic and trizazspiroheterocyclic scaffolds could be independently constructed by a selective N−N bond activation/[ n +1] annulation cascade, a C(sp 2 )‐H activation/[4+1] annulation and a novel tandem C(sp 2 )‐H/C(sp 3 )−H bond activation/[4+1] annulation strategy, along with a broad scope of substrates, moderate to excellent yields and valuable transformations. More importantly, in these transformations, we are the first time to capture a N−N bond activation and a C(sp 3 )−H bond activation of pyrazolidinones under different catalytic system.